Japan’s first ever homegrown passenger jet has had a bumpy few days.

The plane was forced to abort two consecutive test flights to the U.S. over the weekend because of problems with the air management system on board.

It’s the latest setback for the aircraft, the Mitsubishi Regional Jet (MRJ), which has already suffered repeated delays.

Built by Mitsubishi Aircraft Corp., the MRJ is an effort by Japan to compete in the global plane-making industry. It’s the country’s first new commercial aircraft in more than 50 years (the last one was powered by turboprop rather than jet technology).

“We are in the process of finding out the details of the issue we faced during the last two days,” Mitsubishi said Monday. “We are inspecting what the cause is first, and then we will consider the next steps.”

The MRJ was meant to fly from Japan to the U.S. to carry out a series of flight tests.

The company has pushed back delivery plans for the MRJ four times in the past seven years. Its first customer, Japan’s ANA (ALNPY), placed its initial order in 2008, with deliveries scheduled to start in 2013. The airline now isn’t expected to receive the first plane until mid-2018.

Mitsubishi says the jet, which seats as many as 92 passengers, uses 20% less fuel than other aircraft in its class because of its efficient engines and aerodynamic design.

The MRJ puts Mitsubishi in competition with Brazilian plane maker Embraer (ERJ) and Canada’s Bombardier (BDRAF), which dominate the market for passenger jets with fewer than 100 seats.

Delays aren’t uncommon in bringing new planes to market. Industry giants Boeing (BA) and Airbus (EADSF) have both endured embarrassing setbacks on high-profile jets like the 787 Dreamliner and the A380.